1. Field of the Invention
The present invention relates to oral compositions which contain ingredients which upon contact with each other will produce an effervescent effect.
2. The Related Art
More particularly, the present invention relates to oral compositions which consist of a first composition containing one of the ingredients necessary to produce an effervescent effect, and a second composition containing the other ingredient necessary to produce the effervescent effect.
Oral products consisting of a first composition and a second composition, each composition containing separated reactive components which, when brought together develop effervescence are already known in the art. Thus, in GB-A-2,112,642 (Colgate), a dual-compartment dentifrice dispensing container is described which contains in one compartment a portion of the dentifrice containing as reactive component sodium bicarbonate, and in the other compartment another portion of the dentifrice containing as reactive component an acidic compound.
Upon dispensing the two dentifrice portions from the container through a single outlet orifice, the two portions are brought into intimate contact, and the sodium bicarbonate and acidic compound react with each other, thereby releasing carbon dioxide gas which causes the dentifrice to effervesce when used in the mouth.
The first portion of this dentifrice, that is the portion containing the sodium bicarbonate, contains at least about 15% by weight of sodium bicarbonate, and preferably from 20-40% by weight.
One of the drawbacks of sodium bicarbonate is its salty taste, and this is acknowledged in the above GB-A-2,112,642. Formulations according to this patent are stated to have an initial salty taste, which changed to a pleasingly sweeter flavour during brushing, caused by the effervescence.
According to WO-A-95/02392 (Unilever), lowering the sodium bicarbonate level resulted in a significantly less salty taste, without any significant reduction of effervescence. This provided for a dentifrice with an improved consumer acceptability in that it combined the required effervescence with a significantly more pleasant, less salty taste.
In WO-A-96/19189 (Lingner & Fischer) similar compositions are described. It is stated in this prior proposal that during the cleaning procedure all the regions of the surface of the teeth are contacted uniformly by these compositions. The distribution of the active ingredient obtainable during the teeth cleaning procedure is stated to be optimised, due to the intensive formation of foam.
The level of the acidic compound, used in the formulations according to the above prior proposals, generally range from 1-20% by weight of the composition comprising the acidic compound, preferably 3-10% by weight. Since the composition comprising the bicarbonate and the composition comprising the acidic compound are usually and advantageously combined with each other in a volumetric ratio of 1:1, the lower level of the acidic compound, calculated on the total oral care composition is about 0.5% by weight, depending upon the densities of the first and second composition of the oral care product.